textproduct: Albany

SYNOPSIS

Widespread moderate to heavy snow begins early tomorrow morning through very early Wednesday morning, resulting from a coastal low pressure system. Drier, but colder, conditions return Wednesday before additional, light snow showers spread into the region Wednesday night in association with a cold front. After a dry end to the work week, another coastal system takes shape for the weekend, but the probability of impacts to eastern New York and western New England is low.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Key Message:

- Winter Storm Watches have been upgraded to Winter Storm Warnings and Advisories for most of eastern New York and western New England from 7 AM Tuesday through 1 AM Wednesday.

- Expected snowfall totals range from about 2 to 11 inches of snow are anticipated across eastern New York and western New England with the heaviest totals anticipated to fall across the Eastern Catskills, Greater Capital District, Lake George-Saratoga Region, Berkshires, and southern Vermont.

- Within those areas of greatest snowfall, moderate to heavy snowfall rates of 0.5" to 1" per hour are expected from mid/late morning through late afternoon/early evening tomorrow.

Discussion: Surface high pressure centered across the eastern Great Lakes has maintained pleasant, though brisk, conditions across the region today ahead of a highly anticipated winter storm. Throughout the afternoon and into this evening, as the high drifts eastward overhead, breezy winds will begin to decline whilst clouds increase from west to east. Low temperatures tonight, despite increasing cloud cover, will be rather chilly with values in the tens to 20s.

While the aforementioned surface high traverses the Northeast this evening, a positively-tilted, southern-stream shortwave will deepen across the Southern Plains/Southeast regions, owing to a surface response in the development of a weak area of surface low pressure in the Deep South near the northern Gulf. Simultaneously, a northern-stream shortwave will become neutrally tilted across the upper Midwest/western Great Lakes regions. Alignment of the axis of the neutrally-tilted, northern-stream disturbance and the forward flank of the one associated with the southern- stream will create a southwest to northeast-oriented moisture axis that will surge northward along the East Coast and into the region from its Gulf origin. With the aforementioned surface high having exited into New England, stratiform precipitation will spread into the region from west to east near the western Mohawk Valley and Southwest Adirondacks between 4 and 6 AM, initially as a result of increased cyclonic vorticity advection in advance of the northern-stream shortwave. However, with isentropic lift increasing from south to north ahead of the warm front of the ares of low pressure, precipitation will start filling in to the south by 6-8 AM. With temperatures remaining at or below freezing within these onset periods, precipitation is expected to be snow for everyone to start. Additionally, snow will also be light to start as forcing for ascent remains weaker.

By mid-morning tomorrow, the aforementioned area of low pressure looks to begin its inland exit, deepening fairly rapidly as it enters the western Atlantic. As the northern-stream shortwave nears and the now coastal low deepens along its northeasterly track, forcing for ascent will increase with bands of low-level FGEN taking shape across the eastern Catskills, north and east through the Capital District and into western New England. Latest forecast soundings and atmospheric cross sections indicate decent omega intersecting the DGZ as well as some areas where FGEN intersects the DGZ, supporting efficient snow production processes. Upslope flow within the higher terrain of the Eastern Catskills, Southern Greens, and Berkshires will also help to enhance vertical ascent in these areas. One concern that we had for this forecast was the potential for downsloping into the Capital District courtesy of southwest flow off the surrounding higher terrain. However, seeming to overcome the effects of this is not only the presence of low-level FGEN bands, but the strong divergence located within the favored right entrance region of an anticyclonically curved jet aloft. Additionally, based on the consensus of a more northwesterly (closer inland) track of the low, the probability of the Capital District, Lake George-Saratoga Region, Eastern Catskills, Southern Vermont, and Berkshires being in a favored position for strong deformation bands is moderate to high. In fact, the latest HREF highlights these areas as seeing prolonged 0.5 to 1 and possibly as high as 1.5 inch per hour snowfall rates tomorrow morning through tomorrow afternoon. Therefore, we had the greatest confidence in seeing the highest snowfall totals of 7 to 11 inches within these areas through late Tuesday night. Elsewhere, light to moderate accumulations of 2 to 6 inches looks more likely, especially since, for areas within the lower Mid-Hudson Valley, southern Litchfield County, and far- southern Berkshire County will see some rain mix in as temperatures diurnally warm.

As this is a fairly progressive system, snow should taper off, as previously mentioned, through late Tuesday night as the causing system swiftly departs to the northeast. Highs Tuesday will span the upper 20s to low/mid 30s. Wednesday will then be a much drier day as high pressure builds in at the surface with flat ridging aloft. Temperatures will remain on the cool side with similar values, though a couple degrees "warmer", than Tuesday. Lows Wednesday night will fall back to the tens and 20s with chances of precipitation increasing once again, this time from northwest to southeast, in advance of a cold front draping down from a low traversing northern Quebec. All snow is anticipated once again as the precipitation type, and will be concentrated mainly within, north and west of the Capital District.

LONG TERM /THURSDAY THROUGH SUNDAY/

Snow showers from the aforementioned cold front linger into Thursday, with some light, upslope and lake effect showers contributing additional accumulations of 1-2" or so in the Southwest Adirondacks and upslope regions of the Southern Green Mountains. Accumulations elsewhere look to be slim to none. High temperatures Thursday will be in the 20s and 30s.

Upon the passage of the cold front Thursday, high pressure builds in across the region Thursday night, bringing fair weather once again for the end of the work week. Arctic cold air moves in behind the cold front however, with low temperatures Thursday night looking to fall into the negative and single digits for the first time this season. Highs Friday will then only rise into the tens and 20s. Dry conditions linger into at least part of the night Friday with lows dropping into the single digits to tens.

The forecast for the weekend retains a fair amount of uncertainty at this time. Medium to long range guidance shows another coastal system developing Saturday, but most keep it well south of our area such that no impacts from it occur at all. One or two models show the storm clipping some of our southern areas, but the overall probability of just 0.1" of snow is around 20%. Therefore, we did not deviate from the latest run of the NBM, which favors additional snow showers from another northern-stream shortwave and cold front Saturday into Sunday. Highs Saturday and Sunday will be in the 20s and 30s with lows in the 10s and 20s Saturday night and single digits to 10s Sunday night.

AVIATION /18Z MONDAY THROUGH SATURDAY/

VFR conditions continue for all TAF sites through 11z. A coastal storm arrives between 11z and 13z across all TAF sites bringing widespread snowfall. Conditions rapidly deteriorate due to low vsibilities from falling snow between 12z and 15z becoming IFR to LIFR. LIFR conditions continue through 02/18z.

Through 00z, winds continue to be breezy between 10 and 20 knots. Winds are forecasted to be light and variable thereafter and through the end of the TAF period.

Outlook...

Tuesday Night: Moderate Operational Impact. Chance of SN. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Breezy. Chance of SHSN. Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. Friday Night: Moderate Operational Impact. Chance of SN. Saturday: Moderate Operational Impact. Chance of SN.

ALY WATCHES/WARNINGS/ADVISORIES

CT...Winter Weather Advisory from 7 AM Tuesday to 1 AM EST Wednesday for CTZ001. NY...Winter Weather Advisory from 7 AM Tuesday to 1 AM EST Wednesday for NYZ032-033-038>040-042-043-047-060-061- 064>066-082. Winter Storm Warning from 7 AM Tuesday to 1 AM EST Wednesday for NYZ041-048>054-058-059-063-083-084. MA...Winter Storm Warning from 7 AM Tuesday to 1 AM EST Wednesday for MAZ001-025. VT...Winter Storm Warning from 7 AM Tuesday to 1 AM EST Wednesday for VTZ013>015.